jsHint Cleanup and New Filters

I cleaned up all of the jsHint errors except for 2 (in `Unit.js`).

I also created 7 filters in `Colors.js` and tests for them in `visualTest.js`. 6 of the filters work with a specific color (red, green, blue) and show or hide that color. The other filter is for shifting the hue of the image. I had to add a parameter of how much to shift the hue.

I tried my best to follow your naming conventions and coding/commenting style but let me know if you think it's too different.

The unit tests (`unitTests.html`) didn't seem like it was working. I ran the tests in your latest and the results agreed with mine but the number in the green box is only at 2. I was expecting 724. Does this seem right?